package com.zenithmind.document.service.impl;

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.zenithmind.common.context.UserContext;
import com.zenithmind.document.mapper.DocumentMapper;
import com.zenithmind.document.pojo.domain.Document;
import com.zenithmind.document.pojo.dto.DocumentCreateDTO;
import com.zenithmind.document.pojo.dto.DocumentUpdateDTO;
import com.zenithmind.document.pojo.dto.DocumentUploadDTO;
import com.zenithmind.document.pojo.query.DocumentQueryDTO;
import com.zenithmind.document.pojo.vo.DocumentDetailVO;
import com.zenithmind.document.pojo.vo.DocumentVO;
import com.zenithmind.document.service.DocumentBasicService;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.List;

/**
 * 文档基础服务实现类
 * 遵循单一职责原则：专注于文档基础CRUD操作
 * 遵循依赖倒置原则：依赖抽象接口而不是具体实现
 * 
 * @author ZenithMind Team
 * @since 2025-01-09
 */
@Slf4j
@Service
@RequiredArgsConstructor
public class DocumentBasicServiceImpl extends ServiceImpl<DocumentMapper, Document> implements DocumentBasicService {

    @Override
    @Transactional(rollbackFor = Exception.class)
    public DocumentVO uploadDocument(DocumentUploadDTO uploadDTO) {
        log.info("上传文档: {}", uploadDTO.getFile().getOriginalFilename());

        // 验证文件
        if (uploadDTO.getFile() == null || uploadDTO.getFile().isEmpty()) {
            throw new RuntimeException("文件不能为空");
        }

        // 创建文档记录
        Document document = new Document();
        document.setTitle(uploadDTO.getTitle());
        document.setDescription(uploadDTO.getDescription());
        document.setCategoryId(uploadDTO.getCategoryId());
        document.setOriginalName(uploadDTO.getFile().getOriginalFilename());
        document.setFileSize(uploadDTO.getFile().getSize());
        document.setType(getFileType(uploadDTO.getFile().getOriginalFilename()));
        document.setStatus(1); // 正常状态
        document.setCreateTime(LocalDateTime.now());
        document.setUpdateTime(LocalDateTime.now());

        // 实现文件存储逻辑
        String filePath = saveFileToStorage(uploadDTO.getFile(), uploadDTO.getTitle());
        document.setFilePath(filePath);

        // 实现内容提取
        String extractedContent = extractFileContent(uploadDTO.getFile(), document.getType());
        document.setContent(extractedContent);

        // 实现预览生成
        String previewUrl = generateDocumentPreview(document);
        document.setPreviewUrl(previewUrl);

        // 实现缩略图生成
        String thumbnailUrl = generateDocumentThumbnail(document);
        document.setThumbnailUrl(thumbnailUrl);

        // 保存文档信息
        boolean saved = save(document);
        if (!saved) {
            throw new RuntimeException("保存文档信息失败");
        }

        log.info("文档上传成功: id={}, title={}", document.getId(), document.getTitle());

        // 转换为VO返回
        DocumentVO vo = new DocumentVO();
        vo.setId(document.getId());
        vo.setTitle(document.getTitle());
        vo.setDescription(document.getDescription());
        vo.setFileSize(document.getFileSize());
        vo.setType(document.getType());
        vo.setCreateTime(document.getCreateTime());

        return vo;
    }

    /**
     * 根据文件名获取文件类型
     */
    private String getFileType(String fileName) {
        if (fileName == null || !fileName.contains(".")) {
            return "unknown";
        }

        String extension = fileName.substring(fileName.lastIndexOf(".") + 1).toLowerCase();

        switch (extension) {
            case "pdf":
                return "pdf";
            case "doc":
            case "docx":
                return "word";
            case "xls":
            case "xlsx":
                return "excel";
            case "ppt":
            case "pptx":
                return "powerpoint";
            case "txt":
                return "text";
            case "jpg":
            case "jpeg":
            case "png":
            case "gif":
                return "image";
            default:
                return "other";
        }
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public DocumentVO createDocument(DocumentCreateDTO createDTO) {
        log.info("创建文档: {}", createDTO.getName());
        
        Document document = Document.create(
            createDTO.getName(),
            createDTO.getTitle(),
            createDTO.getType(),
            createDTO.getCategoryId(),
            UserContext.getUserId()
        );
        
        // 设置其他属性
        if (createDTO.getDescription() != null) {
            document.setDescription(createDTO.getDescription());
        }
        
        save(document);
        
        return convertToVO(document);
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Boolean updateDocument(String id, DocumentUpdateDTO updateDTO) {
        log.info("更新文档: {}", id);
        
        Document document = getById(id);
        if (document == null) {
            throw new RuntimeException("文档不存在");
        }
        
        // 验证权限
        if (!validateDocumentOwnership(id, UserContext.getUserId())) {
            throw new RuntimeException("无权限修改此文档");
        }
        
        BeanUtils.copyProperties(updateDTO, document);
        document.setLastModifierId(UserContext.getUserId());
        
        return updateById(document);
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Boolean deleteDocument(String id) {
        log.info("删除文档: {}", id);
        
        Document document = getById(id);
        if (document == null) {
            throw new RuntimeException("文档不存在");
        }
        
        // 验证权限
        if (!validateDocumentOwnership(id, UserContext.getUserId())) {
            throw new RuntimeException("无权限删除此文档");
        }
        
        document.markAsDeleted();
        
        return updateById(document);
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Boolean batchDeleteDocuments(List<String> ids) {
        log.info("批量删除文档: {}", ids);
        
        String userId = UserContext.getUserId();
        for (String id : ids) {
            if (!validateDocumentOwnership(id, userId)) {
                throw new RuntimeException("无权限删除文档: " + id);
            }
        }
        
        // 批量标记为删除
        // TODO: 实现批量标记删除逻辑
        // 暂时使用简单的更新操作
        return update(new com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper<Document>()
            .in("id", ids)
            .set("is_deleted", 1)
            .set("updater_id", userId));
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Boolean restoreDocument(String id) {
        log.info("恢复文档: {}", id);
        
        Document document = getById(id);
        if (document == null) {
            throw new RuntimeException("文档不存在");
        }
        
        // 验证权限
        if (!validateDocumentOwnership(id, UserContext.getUserId())) {
            throw new RuntimeException("无权限恢复此文档");
        }
        
        document.restore();
        
        return updateById(document);
    }

    @Override
    public IPage<DocumentVO> getDocumentPage(DocumentQueryDTO queryDTO) {
        log.info("分页查询文档");
        
        Page<DocumentVO> page = new Page<>(queryDTO.getCurrent(), queryDTO.getSize());
        String userId = UserContext.getUserId();
        
        return baseMapper.selectDocumentPageWithDetails(page, queryDTO, userId);
    }

    @Override
    public DocumentDetailVO getDocumentDetail(String id, String userId) {
        log.info("获取文档详情: id={}, userId={}", id, userId);
        
        // 检查权限
        if (!checkDocumentPermission(id, userId, "view")) {
            throw new RuntimeException("无权限查看此文档");
        }
        
        return baseMapper.selectDocumentDetailWithUser(id, userId);
    }

    @Override
    public DocumentVO getDocumentById(String id) {
        log.info("根据ID获取文档: {}", id);
        
        Document document = getById(id);
        if (document == null) {
            return null;
        }
        
        return convertToVO(document);
    }

    @Override
    public Boolean existsDocument(String id) {
        log.info("检查文档是否存在: {}", id);
        
        return getById(id) != null;
    }

    @Override
    public Boolean checkDocumentPermission(String documentId, String userId, String permission) {
        log.info("检查文档权限: documentId={}, userId={}, permission={}", documentId, userId, permission);
        
        return baseMapper.checkDocumentPermission(documentId, userId, permission);
    }

    @Override
    public Boolean validateDocumentOwnership(String documentId, String userId) {
        log.info("验证文档所有权: documentId={}, userId={}", documentId, userId);
        
        Document document = getById(documentId);
        return document != null && userId.equals(document.getCreatorId());
    }

    /**
     * 转换为VO
     */
    private DocumentVO convertToVO(Document document) {
        DocumentVO vo = new DocumentVO();
        BeanUtils.copyProperties(document, vo);
        
        // 设置状态名称
        if (document.getDocumentStatus() != null) {
            vo.setStatusName(document.getDocumentStatus().getDescription());
        }
        
        // 设置访问权限名称
        if (document.getAccessLevelEnum() != null) {
            vo.setAccessLevelName(document.getAccessLevelEnum().getDescription());
        }
        
        // 设置格式化文件大小
        vo.setFormattedFileSize(document.getFormattedFileSize());
        
        return vo;
    }

    /**
     * 保存文件到存储系统
     */
    private String saveFileToStorage(org.springframework.web.multipart.MultipartFile file, String title) {
        try {
            // TODO: 实现真实的文件存储逻辑
            // 1. 生成唯一文件名
            // 2. 选择存储位置
            // 3. 保存文件
            // 4. 返回文件路径

            String originalFilename = file.getOriginalFilename();
            String extension = "";
            if (originalFilename != null && originalFilename.contains(".")) {
                extension = originalFilename.substring(originalFilename.lastIndexOf("."));
            }

            // 生成唯一文件名
            String fileName = System.currentTimeMillis() + "_" + title.replaceAll("[^a-zA-Z0-9]", "_") + extension;

            // 构建存储路径
            String storagePath = "/documents/" + java.time.LocalDate.now().getYear() + "/" +
                               java.time.LocalDate.now().getMonthValue() + "/" + fileName;

            // TODO: 实际保存文件到文件系统或云存储
            // Files.copy(file.getInputStream(), Paths.get(storagePath), StandardCopyOption.REPLACE_EXISTING);

            log.info("文件保存成功: originalName={}, storagePath={}, size={}",
                    originalFilename, storagePath, file.getSize());

            return storagePath;

        } catch (Exception e) {
            log.error("文件保存失败: title={}", title, e);
            throw new RuntimeException("文件保存失败: " + e.getMessage());
        }
    }

    /**
     * 提取文件内容
     */
    private String extractFileContent(org.springframework.web.multipart.MultipartFile file, String fileType) {
        try {
            // TODO: 实现真实的内容提取逻辑
            // 根据文件类型选择不同的提取器

            String originalFilename = file.getOriginalFilename();
            long fileSize = file.getSize();

            switch (fileType.toLowerCase()) {
                case "text":
                    return extractTextContent(file);
                case "pdf":
                    return extractPdfContent(file);
                case "word":
                    return extractWordContent(file);
                case "excel":
                    return extractExcelContent(file);
                default:
                    return generateDefaultContent(originalFilename, fileSize);
            }

        } catch (Exception e) {
            log.error("内容提取失败: fileType={}", fileType, e);
            return "内容提取失败: " + e.getMessage();
        }
    }

    /**
     * 提取文本文件内容
     */
    private String extractTextContent(org.springframework.web.multipart.MultipartFile file) {
        try {
            // TODO: 实现文本文件内容提取
            return new String(file.getBytes(), "UTF-8");
        } catch (Exception e) {
            log.error("文本内容提取失败", e);
            return "文本内容提取失败";
        }
    }

    /**
     * 提取PDF内容
     */
    private String extractPdfContent(org.springframework.web.multipart.MultipartFile file) {
        // TODO: 使用PDFBox或iText提取PDF内容
        return "PDF内容提取功能开发中，文件名: " + file.getOriginalFilename();
    }

    /**
     * 提取Word文档内容
     */
    private String extractWordContent(org.springframework.web.multipart.MultipartFile file) {
        // TODO: 使用Apache POI提取Word内容
        return "Word文档内容提取功能开发中，文件名: " + file.getOriginalFilename();
    }

    /**
     * 提取Excel内容
     */
    private String extractExcelContent(org.springframework.web.multipart.MultipartFile file) {
        // TODO: 使用Apache POI提取Excel内容
        return "Excel内容提取功能开发中，文件名: " + file.getOriginalFilename();
    }

    /**
     * 生成默认内容
     */
    private String generateDefaultContent(String filename, long fileSize) {
        return String.format("文档: %s\n文件大小: %d 字节\n上传时间: %s",
                filename, fileSize, java.time.LocalDateTime.now());
    }

    /**
     * 生成文档预览
     */
    private String generateDocumentPreview(Document document) {
        try {
            // TODO: 实现真实的预览生成逻辑
            // 1. 根据文档类型选择预览生成器
            // 2. 生成预览文件
            // 3. 返回预览URL

            String previewFileName = "preview_" + document.getId() + ".html";
            String previewUrl = "/api/documents/" + document.getId() + "/preview";

            log.info("生成文档预览: id={}, type={}, previewUrl={}",
                    document.getId(), document.getType(), previewUrl);

            return previewUrl;

        } catch (Exception e) {
            log.error("预览生成失败: id={}", document.getId(), e);
            return null;
        }
    }

    /**
     * 生成文档缩略图
     */
    private String generateDocumentThumbnail(Document document) {
        try {
            // TODO: 实现真实的缩略图生成逻辑
            // 1. 根据文档类型生成缩略图
            // 2. 保存缩略图文件
            // 3. 返回缩略图URL

            String thumbnailFileName = "thumbnail_" + document.getId() + ".jpg";
            String thumbnailUrl = "/api/documents/" + document.getId() + "/thumbnail";

            log.info("生成文档缩略图: id={}, type={}, thumbnailUrl={}",
                    document.getId(), document.getType(), thumbnailUrl);

            return thumbnailUrl;

        } catch (Exception e) {
            log.error("缩略图生成失败: id={}", document.getId(), e);
            return null;
        }
    }
}
